This application for collaborative U.S.-Russia research on HIV prevention among migrant women in the Russian Federation is submitted to the NIH in conjunction with a parallel application submitted by the Russian collaborators to the Russian Foundation for Basic Research. It builds upon the international team's completed and current NIH-supported pilot work in Russia as well as the US investigators' extensive cross-national research on migration and HIV. It proposes a novel combination of population-level quantitative and qualitative analyses with analyses of institutional dynamics to describe HIV risks of irregular female migrants from three Central Asian countries- Kyrgyzstan, Tajikistan, and Uzbekistan and to identify challenges and barriers in HIV prevention and mitigation faced by this vulnerable group. Specifically, the study will collect statistically representative survey data on migrant women from Central Asia in two Russian cities recruited through respondent driven sampling and qualitative information from a subsample of those women and their sexual partners. In addition, institutional ethnographies, including interviews with service providers and observations of provider-client interactions, will be carried out at clinics offering sexual and reproductive health and HIV/STI services to migrant women. The analyses will focus on: women's negotiation of HIV risk reduction with their sexual partners; women's use of their personal networks to obtain information about HIV risks and prevention, to evaluate their risks, and to take actions aimed at reducing those risks; and women's interactions with the formal health care sector and the provider- client gaps and disconnects that characterize those interactions. The results of this exploratory study will lay the foundation for subsequent design and testing of culturally-grounded, gender-sensitive, nationally-scalable interventions aimed at reducing the risks of HIV infection among migrant women and improving their access to HIV counseling, testing, and treatment services.